I'm not sure but I think some of it this extra thrust requirement comes from compensating for the mass of the 5m fairing around the Centaur. I believe that CST-100 has turned out heavier than initially projected too.

Sorry I disagree don't think the need for the Solid(s) is there. If anything the CST-100 should be the most refined of the players.

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I'm not sure but I think some of it this extra thrust requirement comes from compensating for the mass of the 5m fairing around the Centaur. I believe that CST-100 has turned out heavier than initially projected too.

Sorry I disagree don't think the need for the Solid(s) is there. If anything the CST-100 should be the most refined of the players.

Well that's what makes it double confusing then about this need for SRBs for it on the Atlas V.

I'm not sure but I think some of it this extra thrust requirement comes from compensating for the mass of the 5m fairing around the Centaur. I believe that CST-100 has turned out heavier than initially projected too.

Sorry I disagree don't think the need for the Solid(s) is there. If anything the CST-100 should be the most refined of the players.

Well that's what makes it double confusing then about this need for SRBs for it on the Atlas V.

Why is it confusing that Prober is wrong?

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Chris Whoever loves correction loves knowledge, but he who hates reproof is stupid.

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I'm not sure but I think some of it this extra thrust requirement comes from compensating for the mass of the 5m fairing around the Centaur. I believe that CST-100 has turned out heavier than initially projected too.

Sorry I disagree don't think the need for the Solid(s) is there. If anything the CST-100 should be the most refined of the players.

Well that's what makes it double confusing then about this need for SRBs for it on the Atlas V.

Why is it confusing that Prober is wrong?

So they can't launch this then without the use of SRBs, though how many seems up for debate.

...adding another SRB doesn't improve reliability compared to a similar vehicle launched without one. How is this really in question?

I agree it probably has negligible effect on reliability, though. Atlas V is one of the most reliable launch vehicles on record.

Isn't the issue about failure modes of the SRBs?

Can capsule survive / LAS get away from a detonating SRB?

Cheers, Martin

Of course, those solid boosters must light after the RD-180, so there is already confidence in the liquid portion of the first stage. The RD-180 can be shut down if a SRB failure is detected. Of course, a SRB failure might also take out the Atlas core tank, even with the RD-180 shut down. Either way, the thrust required to get away from an exploding core must be greater than what those Aerojet SRBs can generate. We're not talking Shuttle SRBs here. These things are relatively small. If the CST-100 can get away from a core failure, it should be able to get away from an SRB failure.

I've seen illustrations of everything from 402 to 422, so who knows what it will end up being. Too much speculation. It definitely is not a 5xx though.

We had an official NASA presentation that said the 412. That's the latest information that we have. The 422 is speculation based on the image. Some speculated (on a prior image) that the image shows the 422 because it looks better with two boosters.

I've seen illustrations of everything from 402 to 422, so who knows what it will end up being. Too much speculation. It definitely is not a 5xx though.

We had an official NASA presentation that said the 412. That's the latest information that we have. The 422 is speculation based on the image. Some speculated (on a prior image) that the image shows the 422 because it looks better with two boosters.

TY yg1968 - it always amazes me how well connected this community is - would it be possible to post some portion of the document in L2?

Just to re-cap (because I'm a little slow)CST-100 uses a LV with single SRB on a Atlas V (412 configuration),Dragon uses a LV with no SRB's on a Falcon 9, andDC uses (as presented) a LV with no SRB's on a Atlas V (402 configuration).the plot thickens...

Just to re-cap (because I'm a little slow)CST-100 uses a LV with single SRB on a Atlas V (412 configuration),Dragon uses a LV with no SRB's on a Falcon 9, andDC uses (as presented) a LV with no SRB's on a Atlas V (402 configuration).the plot thickens...

If you want to confuse yourself a little more, the Atlas V / Centaur puts CST-100 into orbit, while the DC fires it's hybrid engines after being released from the second stage to get to orbit.

If you are counting engines to orbit, it's 10 for Dragon, 4 for CST-100, 5 (2 hybrids) for Dream Chaser.

On page 4 of this presentation it mentions "Solar Panels (Mission Kit)" pictured on the bottom of the service module. Is this a new development as I thought the CST-100 was battery only... Or is this an option for longer duration missions or something?

A good find! Yes, it would appear to be for longer duration missions. But the location is a bit odd, and would require a limited attitude options for using them. (see attached image from the PDF)

Thank you for posting this, but one bit seems confusing.

What is being shown in the center under the heading "Clam Shell CM Design allows easy hardware integration"?

Are they saying that the pressure vessel splits at its widest point to allow access before each launch? With full atmospheric pressure* that joint is resisting nearlytwo million Newtons (101 kPa * 2.5^2 m^2 * Pi) or a half million pounds of force (14.7 PSI*(2.5 M*40 in/m)^2*Pi). That would indeed be convenient but looks hard to implement.

*"Sea level is for sissies"

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What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Assuming the 401/402 can lift the CST-100 to LEO, how much delta-V/altitude increase would be provided by SRBs, in either 1/2/3/4/5 configuration?

No, because there is no need for different delta-V/altitudes

Are you suggesting that CST-100 is built with a single destination in mind? Bigelow Destiny I and II are in a ~100km higher orbit than ISS, and different inclination. I would be surprised if Boeing limited the capsule's capabilities so much.

Are you suggesting that CST-100 is built with a single destination in mind? Bigelow Destiny I and II are in a ~100km higher orbit than ISS, and different inclination. I would be surprised if Boeing limited the capsule's capabilities so much.

Bigelow Genesis I and II are in a ~100km higher orbit than ISS. That was to make a more stable since they did not have reboost capabilities and the inclination is not viable for a manned station. The ISS is a max inclination for manned station for the foreseeable future. Bigelow stations will likely be in a loser inclination than the ISS.